Thread cutters for sewing machines are well known in the art. It is also well known in the art to provide thread cutters wherein a suction tube is provided to draw in any excessive threads depending from the workpiece. An example of this type of thread cutter is shown in U.S. Pat. No. 3,143,987 to H. F. Daniel et al, and granted Aug. 11, 1964. In these thread cutters, the movable knife is frequently made of spring steel. The knife is manufactured such that, when assembled, it presses against the fixed blade and the contact pressure between the blades is adjusted by utilizing the resiliency of the knife blade. However, a drawback with this design is that the contact pressure between the knives depends upon the resiliency of the movable knife. To assure severance of the threads, the knives are adjusted with a relatively high contact pressure therebetween. As may be appreciated, this high contact pressure results in rapid wearing of the knives. The rapid wearing of the knives is particularly apparent when the knives are used in high speed machines and wherein the knives are driven continuously.